Materials for printed circuit boards

ABSTRACT

Described herein are dielectric polymer films and printed circuit boards, such as multilayer and high-density interconnect printed circuit board comprising at least one dielectric polymer film.

BACKGROUND

Printed circuit boards including double sided, multilayer, flexible, andhigh-density interconnect printed circuit boards (HDI-PCB) generallyinclude vias to interconnect different layers of the printed circuitboard (PCB). For many systems in which multilayer PCBs, HDI-PCBs areused, it is desirable to reduce the area of the PCB while increasing itsfunctionality. Such advancements are generally driven by miniaturizationof components, driven by mobile computing, 4G and 5G applications,avionics, and military applications. To achieve these goals, successivegenerations of multilayer PCBs and HDI-PCBs have generally used thinnerand thinner dielectric materials, and laser drilled microvias in thecase of HDI or sequential lamination builds.

There are two major failure modes for the vias in PCBs: (1) overstressand (2) low cycle fatigue. Overstress can manifest itself during thereflow process where the temperature of the assembly is typically about250° C. Multiple passes are generally required for the reflow and acombination of overstress and or cyclic fatigue can cause failure of themicrovias. The second failure mode is low cycle fatigue (less than1,000-10,000 cycles) caused by the service conditions, which may, inextreme cases, vary from −55° C. to 135° C. In both failure modes, thekey driver of poor reliability is the large coefficient of thermalexpansion (CTE) differential between the copper and the dielectricmaterial. In PCBs, dielectric materials generally are composites ofglass fabric and resin that have significant anisotropy in which theZ-axis CTE is much higher than in the X and Y directions since thedielectric material is constrained in the X and Y directions (or axis).The stress imposed on the copper interconnect by the Dielectric is afunction of the CTE differential, the modulus of the dielectric, and thetemperature excursion which the interconnect is subjected to. Theapproach so far with the state of the art has been developed to reducethe CTE differential by loading the polymer/resin used in the reinforceddielectric with fillers that help reduce the CTE and/or to increase thecrosslink density. Accordingly, the CTE goes down but is not low enoughto completely reduce the stress, while there are unwanted consequencessuch as a higher glass transition temperature T_(g) and a highermodulus. Additionally, since the dielectrics (prepregs and laminates)used are reinforced with woven or nonwoven fabrics, the dielectrics areinherently anisotropic. Typically, the Z-axis CTE is much higher than Xand Y directions. The Z-axis modulus is dominated by the resin and ismuch lower as compared to that in the X and Y direction which isdominated by the reinforcement such as woven glass cloth. The anisotropyincreases at T_(g) when the CTEs in the X and Y axis drop significantlyand the CTE in the Z axis goes up significantly by much more than wouldhappen in an isotropic material. The Dielectric stays significantlystiff in the Z direction due to the presence of reinforcement. Anisotropic film on the other hand is not subject to these effects. Thecurrent state of the art approach uses higher crosslink density andhigher filler loading thereby increasing the modulus and the T_(g). Thenet effect is that the stresses do not diminish much. To minimize thestress and resulting strain on the interconnect the quantity given bythe product of the differential in CTE, multiplied with the modulus ofthe dielectric multiplied by the differential between the T_(g) andlower end of the excursion needs to be minimized. The current state ofthe art only addresses reducing the differential in CTE an approachwhich results in the unwanted higher modulus and T_(g). There istherefore a need for lower modulus and lower T_(g) systems that can helpreduce the interconnect stress.

There is also a need for printed circuit boards providing data channels(e.g., transmission lines) capable of supporting data rates greater than28 Gbps (e.g., 56, 112, or 224 Gbps/channel). However, one obstacle toachieving such data rates at high fundamental frequencies (e.g., 8-56GHz fundamental frequencies) is the channel loss of conventionaltransmission lines due to the conductor (e.g., copper) and thedielectric used to form and isolate the transmission lines. Currently,differential signaling is used with reinforced laminate materials, whichhave the issue of anisotropy and non-uniform dielectric properties. Thisapproach leads to skew as each transmission line encounters a differenteffective dielectric constant due to the fiber weave effect. Thebandwidth limitation imposed by the narrow conductor width (a result ofrelatively high dielectric constants) and the skew due to reinforcementlead to significant, potentially insurmountable problems with the stateof the art in getting to higher data rates.

The current state of the art striplines used for data transmission rangefrom 3.5-5 mil Dielectric thickness with 18-35-micron thick copper. TheDielectric constants (Dk) for the material are no lower than 3.0 at bestfor woven materials. This is facilitated through the use of low Dkglass. However, any attempts to lower the Dk through the use of lower Dkresin increases Skew. The Dielectric constant of the composite materialis lowered but that of the reinforcement remains the same and that ofthe resin is lowered thereby increasing the gap between the Dk of theresin and the Dk of the reinforcement thereby increasing skew.

Accordingly, there is a need for high-reliability dielectric materialsand printed circuit boards comprising the same that overcome theselimitations.

SUMMARY

Described herein, in part, are dielectric layers and films and their usein printed circuit boards such as antenna, rigid-flex, flex,conventional and high-density interconnect (HDI) printed circuit boards(PCBs). The dielectric films of the present disclosure may, for example,may or may not be reinforced with glass fabric. In some embodiments, thelayers and films each have low T_(g), low modulus (e.g., Young'smodulus, tensile modulus, or elastic modulus), and/or a low dielectricconstant. In some embodiments, the layers and films may have a lowdissipation factor.

It is known in the art that dielectric constants are relatively high inmaterials for buildup layers for use in multilayer printed circuitboards and HDI-PCBs. The present disclosure demonstrates, in part, thatlower dielectric constant materials for PCB layers, particularlydielectric polymer films having a dielectric constant less than or equalto about 2.8, enable wider transmission lines for films of the samedielectric thickness, thereby reducing the insertion loss in the circuitboard.

Furthermore, the glass transition temperature T_(g) in a dielectricpolymer film or layer described herein can be an analog of mechanicalyield point. For example, the CTEs and the moduli of the dielectricfilms can change significantly above T_(g). A lower T_(g) is oftenassociated with a lower yield strength of the dielectric film. Thus, thestress on the interconnect of a PCB (e.g., primarily copper) can besignificantly reduced to be below the yield strength (e.g., of copper)as the film material reaches its T_(g). Furthermore, the use ofthermosetting films with low dielectric constant and/or low dissipationfactor can enable the curing and C staging to be carried out attemperatures below 250° C.

The dielectric polymer films of the present disclosure are alsocharacterized by a relatively low T_(g) and a substantially isotropicrelatively low modulus (e.g., a substantially isotropic Young's modulusof less than 6 GPa or 5 GPa), which, when taken together, have beenshown to improve reliability of the printed circuit boards describedherein, including reductions in overstress and low cycle fatigue asdemonstrated by a reduced anisotropy of the CTE of the films, and lessstrain on the copper connections. In preferred embodiments, the T_(g) ofthe dielectric film described herein is below 120° C. (e.g., below 100°C.). In preferred embodiments, the modulus of a dielectric filmdescribed herein is below 5 GPa. Furthermore, the dielectric polymerfilms of the disclosure may, in some embodiments, have a low dissipationfactor (e.g., 0.005 or less), which has been advantageously found toreduce the dielectric loss, thereby reducing the insertion loss. Thedielectric loss is directly proportional to the square root of thedielectric constant and the dissipation factor and the frequency ofoperations.

Materials having a lower dielectric constant and dissipation factor,when incorporated as dielectric layers and films into a printed circuitboard, are therefore contemplated by the present disclosure to reduceinsertion loss, thereby improving signal integrity. An additionalbenefit of the lower dielectric constant is that it increases the linewidth required for a certain design impedance. This imbues an additionalbenefit to the insertion loss. Furthermore, the conductor loss isinversely related to the line width. The wider the lines the lower theinsertion loss. Lower Dk and Df therefore help with reducing not justthe Dielectric loss but also the conductor loss. It is also contemplatedherein that the use of wider lines due to lower dielectric constant alsohelp to improve process yields, as there is an adverse impact on processyields while making printed circuit boards with thinner lines. As aresult, a polymer film of the present disclosure may possess arelatively low dielectric constant, T_(g), modulus, and/or dissipationfactor as described above and confer the benefits associated with eachproperty as described above. In other embodiments, a polymer film of thepresent disclosure may possess a relatively low dielectric constant,T_(g), modulus, and dissipation factor as described above and maytherefore confer the benefits of improved reliability by virtue ofreduced stress on the interconnects such as vias and microvias as adirect result of lower modulus and T_(g), a lower Dielectric loss due tolow Dk and low Df of the film, a reduced conductor loss due toenablement of wider lines due to low dielectric constant and higherprocess yields enabled by the lower Dielectric constant of the film.These properties enable high density interconnect boards, ultra-highfrequency of operation and ultrahigh data rates in a printed circuitboard. The isotropic nature of the films helps avoid the skew problemsas opposed to the current state of the art where reinforced Dielectricsare used in a printed circuit board. In another embodiment, the printedcircuit boards of the present disclosure are also contemplated to enablehigher data rates and higher frequency operation due to lower insertionloss, increased reliability and increased interconnect density. Thus,the present disclosure, in an embodiment, describes novel transmissionlines that overcome the problems as described herein with the use of aunique configuration of low dielectric constant unreinforced films thatallow the use of wider traces to extend the bandwidth of thecommunication channels with overall reduced thickness and withoutsignificant fiber weave skew.

In one aspect, described herein is a printed circuit board, comprising adielectric layer comprising at least one dielectric polymer film,wherein the at least one dielectric polymer film has: (i) a glasstransition temperature less than or equal to about 130° C.; (ii) adielectric constant less than or equal to about 2.8; and (iii) asubstantially isotropic elastic modulus less than or equal to about 6GPa when the average temperature of the at least one dielectric polymerfilm is below the glass transition temperature.

In some embodiments, the dissipation factor of the at least onedielectric polymer film is from about 0.001 to about 0.005.

In some embodiments, the dielectric constant is from about 1.1 to about2.5.

In some embodiments, the glass transition temperature is from about 25°C. to about 110° C.

In some embodiments, the elastic modulus less than or equal to about 4GPa when the average temperature of the at least one dielectric polymerfilm is below the glass transition temperature.

In some embodiments, the at least one dielectric polymer film forms apart of transmission line structure of the printed circuit board.

In some embodiments, a dissipation factor of the transmission line isless than or equal to about 0.0025 at 5 GHz. In some embodiments, adissipation factor of the transmission line is less than or equal toabout 0.0025 at 10 GHz.

In some embodiments, a width of the transmission line is greater than orequal to about 5 Mils.

In some embodiments, the transmission line is a first transmission line,wherein the at least one dielectric polymer film forms a secondtransmission line of the printed circuit board, and wherein a thicknessof a dielectric layer between the first transmission line and the secondtransmission line is between 0.1 Mils and 4 Mils.

In some embodiments, the circuit board includes at least one componentconfigured to transmit signals via the transmission line using pulseamplitude modulation (PAM).

In some embodiments, a number of pulse amplitude levels used in thepulse amplitude modulation is between 2 and 16.

In some embodiments, the circuit board includes at least one componentconfigured to transmit data via the transmission line at a data rategreater than or equal to about 10 Gbps.

In some embodiments, the transmission line is one of a plurality oftransmission lines formed from the dielectric polymer film, and whereinone or more components of the printed circuit board are configured totransmit data via each transmission line of the plurality oftransmission lines at a data rate greater than or equal to about 10Gbps.

In some embodiments, the circuit board is a component of a computationaldevice or a networking device.

In some embodiments, the computational device is a desktop computer,laptop computer, server, tablet, accelerator, supercomputer, or mobilephone.

In some embodiments, the networking device is a switch, router, accesspoint, or modem.

In some embodiments, the thermal conductivity of the dielectric layer orat least one polymer film is up to 4 w/mk.

In some embodiments, the dielectric polymer film is used to manufacturea double sided, or multilayer antenna.

In some embodiments, the dielectric polymer film is manufactured infilms using continuous solvent cast process.

In some embodiments, the circuit board is a multilayer printed circuitboard or high-density interconnect printed circuit board.

In some embodiments, a coefficient of thermal expansion of thedielectric polymer film is less than 200 ppm/° C. above T_(g).

In some embodiments, a coefficient of thermal expansion of thedielectric polymer film is more than 200 ppm/° C. above T_(g).

In some embodiments, the dielectric polymer film comprises across-linked polymer composition.

In another aspect, disclosed herein is a printed circuit board,comprising: a core layer; a dielectric layer disposed on a first side ofthe core layer, wherein the dielectric layer comprises at least onedielectric polymer film having: (i) a glass transition temperature lessthan or equal to about 130° C.; (ii) a dielectric constant less than orequal to about 2.8; and (iii) a substantially isotropic elastic modulusless than or equal to about 6 GPa when the average temperature of the atleast one dielectric polymer film is below the glass transitiontemperature; and one or more microvias penetrating through thedielectric layer and connecting one or more respective pairs ofconductive traces disposed on opposing sides of the dielectric layer.

In some embodiments, the dielectric layer reduces the risk of failure ofthe one or more microvias due to low cycle fatigue or overstress, ascompared to when the dielectric layer is absent from the high-densityinterconnect printed circuit board.

In some embodiments, the core layer is a fiberglass-based dielectric orlaminate.

In some embodiments, the dielectric layer is a first dielectric layer,and the high-density interconnect printed circuit board furthercomprises a second dielectric layer comprising the at least onedielectric polymer film.

In some embodiments, the circuit board further comprises one or moremicrovias penetrating through the second dielectric layer and connectingone or more respective pairs of conductive traces disposed on opposingsides of the second dielectric layer.

In some embodiments, the second dielectric layer is disposed on a secondside of the core layer.

In some embodiments, the circuit board of claim further comprises: athird dielectric layer disposed on the first dielectric layer andcomprising the at least one dielectric polymer film; and a fourthdielectric layer disposed on the second dielectric layer and comprisingthe at least one dielectric polymer film.

In some embodiments, the second dielectric layer is disposed on thefirst dielectric layer.

In some embodiments, the circuit board is a multilayer printed circuitboard or high-density interconnect printed circuit board.

DETAILED DESCRIPTION

This application refers to various issued patents, published patentapplications, journal articles, and other publications, all of which areincorporated herein by reference. If there is a conflict between any ofthe incorporated references and the instant specification, thespecification shall control.

Dielectric Materials and Films

Generally, the dielectric materials in the presently disclosedembodiments comprise a polymer composition. Dielectric materials includeof the present disclosure, but are not limited to, a dielectric film,layer, or sheet as described herein.

A dielectric layer described herein may comprise, in some embodiments,one or more dielectric polymer films described herein. In someembodiments, a dielectric layer described herein may comprise one, two,three, four, or five dielectric polymer films described herein. In someembodiments, a dielectric layer described herein may comprise fivedielectric polymer films or more described herein.

In some embodiments, the average thickness of a dielectric layerdescribed herein is about 0.1 Mil to about 6.0 Mil (e.g., about 0.1 Milto about 1.0 Mil, about 0.1 Mil to about 2.0 Mil, about 0.1 Mil to about3.0 Mil, about 0.1 Mil to about 4.0 Mil, or about 0.1 Mil to about 5.0Mil). In some embodiments, the average thickness of a dielectric layerdescribed herein is about 0.25 Mil to about 2.5 Mil. In someembodiments, the average thickness of a dielectric layer describedherein is about 0.5 Mil to about 2.0 Mil. In some embodiments, theaverage thickness of a dielectric layer described herein is about 0.5Mil. In some embodiments, the average thickness of a dielectric layerdescribed herein is about 1 Mil. In some embodiments, the averagethickness of a dielectric layer described herein is about 5 Mil to about125 Mil. In some embodiments, the average thickness of a dielectriclayer described herein is about 0.1 Mil, 0.2 Mil, 0.3 Mil, 0.4 Mil, 0.5Mil, 0.6 Mil, 0.7 Mil, 0.8 Mil, 0.9 Mil, 1.0 Mil, 1.1 Mil, 1.2 Mil, 1.3Mil, 1.4 Mil, 1.5 Mil, 1.6 Mil, 1.7 Mil, 1.8 Mil, 1.9 Mil, 2.0 Mil, 3.0Mil, 3.3 Mil, 3.5 Mil, 4.0 Mil, 5.0 Mil, or 6.0 Mil. In someembodiments, the average thickness of a dielectric layer describedherein is about 5, 10, 15, 20, 25, 30, 35, 40, 50, 60, 70, 80, 90, 100,or 125 Mil.

The dielectric materials described herein may vary in properties suchas, but not limited to, glass transition temperature (T g), coefficientof thermal expansion (CTE), the dielectric constant, Young's modulus,film thickness, and thermal conductivity. Exemplary properties of thedielectric materials contemplated by the present disclosure are providedas follows:

In some embodiments, the dielectric films in the present disclosure canbe carried on substrates such as copper foil or PET. Such copper foilcan include a thickness of about 3 to about 35 microns. In someembodiments, the dielectric films can be coated with a 0.5-5.0-micronthick sputtered copper through e.g., a physical vapor depositionprocess. In some embodiments, the present disclosure includes laminatesthat are made by laminating copper foils coated with the dielectricfilms as described herein, followed by pressing them together throughhot roll lamination of pressing using batch processing with a platenpress.

Exemplary Polymers of the Present Disclosure

In an embodiment of the disclosure, a dielectric polymer film describedherein comprises a cross-linked polymer composition. In someembodiments, the cross-linked polymer composition is present in thedielectric polymer film in an amount of about 50% by weight, 55% byweight, 60% by weight, 65% by weight, 70% by weight, 75% by weight, 80%by weight, 85% by weight, 90% by weight, 95% by weight, or 99% by weightbased on the total weight of the film. Said cross-linked polymercompositions as described herein may, in some embodiments, comprise thecross-linked product of a thermosetting polymer. Said thermosettingpolymers comprise one or more functional groups that are capable ofcross-linking with other reactive groups to produce the cross-likedpolymer composition.

In some embodiments, the functional group is a group that is reactivewith a curing agent. In some embodiments, the functional group is avinyl group. In some embodiments, the functional group is within thebackbone of the thermosetting polymer (e.g., a backbone alkenyl group ofa polybutadiene). In some embodiments, the functional group is graftedoff of the thermosetting polymer. In some embodiments, the curing agentis a peroxide agent. In some embodiments, the thermosetting polymer andthe curing agent react to form the cross-linked polymer composition inthe presence of a catalyst. In some embodiments, the thermosettingpolymer and the curing agent react to form the cross-linked polymercomposition without the need for a catalyst. In some embodiments,reaction of the thermosetting polymer and the curing agent occurs underthermal conditions.

Curing agents of the present disclosure include but are not limited tothose useful in initiating cure of the relevant polymers. Examplesinclude, but are not limited to, azides, peroxides, diazo compounds,sulfur, and sulfur derivatives. Free radical agents are especiallydesirable as cure initiators. Examples of free radical agents includeperoxides, hydroperoxides, and non-peroxide initiators such as, but notlimited to, 2,3-dimethyl-2, 3-diphenyl butane. Examples of peroxidecuring agents include dicumyl peroxide, alpha,alpha-di(t-butylperoxy)-m,p-diisopropylbenzene,2,5-dimethyl-2,5-di(t-butylperoxy)hexane-3, and2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, and mixtures comprising oneor more of the foregoing cure initiators. The cure initiator, when used,is typically present in an amount of about 0.25 wt. % to about 15 wt. %,based on the total weight of the thermosetting polymer to be cured.

In some embodiments, the thermosetting polymer is a high vinyl polymerresin (e.g., a polymer resin with greater than 70%, 80%, or 90% of itsconstituent units having vinyl groups). In some embodiments, thethermosetting polymer is a low vinyl polymer resin(e.g., a polymer resinwith less than 70%, 60%, 50%, 40%, or 30% of its constituent unitshaving vinyl groups).

Examples of thermosetting polymers comprising functional groups capableof cross-linkers include but are not limited to polyalkylenes (e.g.,polyethylene, polypropylene, polyisoprenes, polynorborenes, polyalkyleneterephthalates (such as polyethylene terephthalate, polybutyleneterephthalate)), polyalkenylenes such as polybutadienes, and styrenes(e.g., impact-modified polystyrene, acrylonitrile-butadiene-styrene,styrene-acrylonitrile), or their grafted derivatives (e.g, polyethylenegrafted with maleic anhydride).

In some embodiments, the thermosetting polymer is capable ofcross-linking with another thermosetting polymer without a cross-linkingagent to produce the cross-linked polymer composition. Examples ofthermosetting polymers that cross-link with other polymers includepolyalkenylenes (e.g, polybutadienes) and polyalkynylenes, and theirderivatives (e.g., silicon modified).

Examples of thermosetting polymers comprising functional groups capableof cross-linking cross-linkers include but are not limited topolyalkylenes (e.g., polyethylene, polypropylene, polyalkyleneterephthalates (such as polyethylene terephthalate, polybutyleneterephthalate)), polyalkenylenes such as polybutadienes, and styrenes(e.g., impact-modified polystyrene, acrylonitrile-butadiene-styrene,styrene-acrylonitrile).

The dielectric polymer films may also comprise, in some embodiments,cross-linking units a radical acceptor material resulting fromcross-linking with the polymer. Acceptor materials can be incorporatedinto the formulation to modulate the mechanical, physical, or electricalproperties of the dielectric materials in the cured, or uncured state,such as, for example, the brittleness, flow properties, the CTE,adhesion, or other desirable properties the dielectric film (e.g.,acrylates, maleimides, vinyl monomers). In some embodiments the acceptormaterial is a vinyl containing epoxy compound. In some embodiments theacceptor materials is an acrylate or methacrylate monomer. In someembodiments the acceptor materials is bis-acrylate or bis methacrylate.In some embodiments the acceptor materials is poly-acrylate orpoly-methacrylate. In some embodiments the acceptor material isbis-maleimide or a poly-maleimide. In some embodiments, the acceptormaterial is SA9000 (Polyphyenylene ether that has been end-capped withan arcylate).

In some embodiments, a thermosetting polymer composition describedherein further comprises a poly(arylene ether). Exemplary poly(aryleneether)s of the present disclosure include, but are not limited to,poly(2,6-dimethyl-1,4-phenylene ether), poly(2,6-diethyl-1,4-phenyleneether), poly(2,6-dipropyl-1,4-phenylene ether),poly(2-methyl-6-allyl-1,4-phenylene ether),poly(di-tert-butyl-dimethoxy-1,4-phenylene ether),poly(2,6-dichloromethyl-1,4-phenylene ether,poly(2,6-dibromomethyl-1,4-phenylene ether),poly(2,6-di(2-chloroethyl)-1,4-phenylene ether),poly(2,6-ditolyl-1,4-phenylene ether), poly(2,6-dichloro-1,4-phenyleneether), poly(2,6-diphenyl-1,4-phenylene ether), andpoly(2,5-dimethyl-1,4-phenylene ether).

The polymer films further comprise a polybutadiene or polyisoprenepolymer. A “polybutadiene or polyisoprene polymer” as used hereinincludes homopolymers derived from butadiene, homopolymers derived fromisoprene, and copolymers derived from butadiene and/or isoprene and/orless than 50 weight percent (wt %) of a monomer co-curable with thebutadiene and/or isoprene. Suitable monomers co-curable with butadieneand/or isoprene include monoethylenically unsaturated compounds such asacrylonitrile, ethacrylonitrile, methacrylonitrile,alpha-chloroacrylonitrile, beta-chloroacrylonitrile,alpha-bromoacrylonitrile, C₁₋₆ alkyl(meth)acrylates (for example, methyl(meth)acrylate, ethyl (meth)acrylate, n-butyl(meth)acrylate,n-propyl(meth)acrylate, and isopropyl(meth)acrylate), acrylamide,methacrylamide, maleimide, N-methyl maleimide, N-ethyl maleimide,itaconic acid, (meth)acrylic acid, alkenyl aromatic compounds asdescribed below, and combinations comprising at least one of theforegoing monoethylenically unsaturated monomers.

The polymers described herein may be a homopolymer (for example, apolyalkylene or poly(arylene ether) homopolymer) or a copolymer,including a graft or a block copolymer. In some embodiments, thecopolymer is an alternating copolymer. In some embodiments, thecopolymer is a block copolymer.

In some embodiments, block copolymers comprise a block (A) derived froman alkenyl aromatic compound and a block (B) derived from a conjugateddiene. The arrangement of blocks (A) and (B) includes linear and graftstructures, including radial teleblock structures having branchedchains. Examples of linear structures include diblock (A-B), triblock(A-B-A or B-A-B), tetrablock (A-B-A-B), and pentablock (A-B-A-B-A orB-A-B-A-B) structures as well as linear structures containing 6 or moreblocks in total of A and B. Specific block copolymers include diblock,triblock, and tetrablock structures, and specifically the A-B diblockand A-B-A triblock structures.

In some embodiments, the compound used to provide block (A) is analkenyl aromatic compound, such as, for example, one disclosed in U.S.Pat. No. 9,265,160, which is incorporated herein by reference. In someembodiments, the alkenyl aromatic compound is styrene.

In some embodiments, the conjugated dienes used to provide block (B)include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene),2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene, specifically1,3-butadiene and isoprene. A combination of conjugated dienes can beused. The block (B) derived from a conjugated diene is optionallypartially or fully hydrogenated.

Exemplary block copolymers comprising a block (A) derived from analkenyl aromatic compound and block (B) derived from a conjugated dieneinclude styrene-butadiene diblock copolymer (SB),styrene-butadiene-styrene triblock copolymer (SBS), styrene-isoprenediblock copolymer (SI), styrene-isoprene-styrene triblock copolymer(SIS), styrene-(ethylene-butylene)-styrene triblock copolymer (SEBS),styrene-(ethylene-propylene)-styrene triblock copolymer (SEPS), andstyrene-(ethylene-butylene) diblock copolymer (SEB). Such polymers arecommercially available, for example from Shell Chemical Corporationunder the trade names KRATON D-1101, KRATON D-1102, KRATON D-1107,KRATON D-1111, KRATON D-1116, KRATON D-1117, KRATON D-1118, KRATOND-1119, KRATON D-1122, KRATON D-1135X, KRATON D-1184, KRATON D-1144X,KRATON D-1300X, KRATON D-4141, KRATON D-4158, KRATON G1726, and KRATONG-1652.

Other exemplary polymers that may be used in the dielectric filmsdescribed herein are disclosed in U.S. Pat. Nos. 6,890,635 and9,265,160, each of which are incorporated herein by reference.

Glass Transition Temperature (Tg) of Films

In some embodiments, the glass transition temperature T_(g) of thedielectric material is up to about 5, 10, 15, 20, 25, 30, 35, 40, 45,50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, or130° C. In some embodiments, the T_(g) of the dielectric material isless than or equal to about 130° C. In some embodiments, the T_(g) ofthe dielectric material is less than or equal to about 120° C. In someembodiments, the T_(g) of the dielectric material is less than or equalto about 110° C. In some embodiments, the T_(g) of the dielectricmaterial is less than or equal to about 100° C. In some embodiments, theT_(g) of the dielectric material is less than or equal to about 90° C.In some embodiments, the T_(g) of the dielectric material is less thanor equal to about 80° C. In some embodiments, the T_(g) of thedielectric material is less than or equal to about 70° C. In someembodiments, the T_(g) of the dielectric material is less than or equalto about 60° C. In some embodiments, the T_(g) of the dielectricmaterial is less than or equal to about 50° C. In some embodiments, theT_(g) of the dielectric material is less than or equal to about 40° C.In some embodiments, the T_(g) of the dielectric material is less thanor equal to about 30° C. In some embodiments, the T_(g) of thedielectric material is less than or equal to about 25° C. In someembodiments, the T_(g) of the dielectric material is less than or equalto about 20° C. In some embodiments, the T_(g) of the dielectricmaterial is less than or equal to about 10° C. In some embodiments, theT_(g) of the dielectric material is less than or equal to about 5° C. Insome embodiments, the T_(g) of the dielectric material is from about 90°C. to 130° C. In some embodiments, the T_(g) of the dielectric materialis from about 90° C. to 120° C. In some embodiments, the T_(g) of thedielectric material is from about 80° C. to 110° C. In some embodiments,the T_(g) of the dielectric material is from about 70° C. to 100° C. Insome embodiments, the T_(g) of the dielectric material is from about 60°C. to 90° C. In some embodiments, the T_(g) of the dielectric materialis from about 50° C. to 80° C. In some embodiments, the T_(g) of thedielectric material is from about 40° C. to 70° C. In some embodiments,the T_(g) of the dielectric material is from about 30° C. to 60° C. Insome embodiments, the T_(g) of the dielectric material is from about 25°C. to 50° C. In some embodiments, the T_(g) of the dielectric materialis from about 20° C. to 50° C. In some embodiments, the T_(g) of thedielectric material is from about 10° C. to 40° C. In some embodiments,the T_(g) of the dielectric material is from about 5° C. to 40° C.

Coefficient of Thermal Expansion (CTE) of Films

In some embodiments, the coefficient of thermal expansion (CTE) of thedielectric material from 50 to 250° C. is up to about 50, 60, 70, 80,90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220,230, 240, 250, 260, 270, 280, 290 or 300 ppm/° C. In some embodiments,the CTE is up to about 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120,130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260,270, 280, 290 or 300 ppm/° C. below the T_(g) of the dielectricmaterial. In some embodiments, the CTE is up to about 80, 90, 100, 110,120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 240,250, 260, 270, 280, 290 or 300 ppm/° C. above the T_(g) of thedielectric material. In some embodiments, the CTE is up to about 50, 60,70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210,220, 230, 240, 250, 260, 270, 280, 290 or 300 ppm/° C. In someembodiments, the CTE is up to about 20, 30, 40, 50, 60, 70, 80, 90, 100,110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240,250, 260, 270, 280, 290 or 300 ppm/° C. below the T_(g) in a curedthermoset composition. In some embodiments, the coefficient of thermalexpansion is about 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180,190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290 or 300 ppm/° C.above the T_(g) in a cured thermoset composition. In some embodiments,the CTE of the dielectric material is less than or equal to 220 ppm/° C.below the T_(g) of the dielectric material. In some embodiments, the CTEof the dielectric material is less than or equal to 200 ppm/° C. belowthe T_(g) of the dielectric material. In some embodiments, the CTE ofthe dielectric material is less than or equal to 180 ppm/° C. below theT_(g) of the dielectric material. In some embodiments, the CTE of thedielectric material is less than or equal to 160 ppm/° C. below theT_(g) of the dielectric material. In some embodiments, the CTE of thedielectric material is less than or equal to 140 ppm/° C. below theT_(g) of the dielectric material. In some embodiments, the CTE of thedielectric material is less than or equal to 120 ppm/° C. below theT_(g) of the dielectric material. In some embodiments, the CTE of thedielectric material is less than or equal to 100 ppm/° C. below theT_(g) of the dielectric material. In some embodiments, the CTE of thedielectric material is from about 90 to about 120 ppm/° C. below theT_(g) of the dielectric material. In some embodiments, the CTE of thedielectric material is from about 120 to about 150 ppm/° C. below theT_(g) of the dielectric material. In some embodiments, the CTE of thedielectric material is from about 70 to about 100 ppm/° C. below theT_(g) of the dielectric material. In some embodiments, the CTE of thedielectric material is from about 60 to about 90 ppm/° C. below theT_(g) of the dielectric material. In some embodiments, the CTE of thedielectric material is from about 20 to about 60 ppm/° C. below theT_(g) of the dielectric material. In some embodiments, the CTE of thedielectric material is from about 10 to about 50 ppm/° C. below theT_(g) of the dielectric material. In some embodiments, the CTE of thedielectric material is substantially isotropic.

Dielectric Constant (Dk) of Films

In some embodiments, the dielectric constant of a dielectric materialdescribed herein, such as a dielectric layer or film, is about 1.1, 1.2,1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7,2.8. In some embodiments, the dielectric constant of a cured thermosetcomposition in the presently disclosed embodiments is about 1, 1.1, 1.2,1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7,or 2.8. In some embodiments, the dielectric constant is less than orequal to 2.8. In some embodiments, the dielectric constant is less thanor equal to 2.7. In some embodiments, the dielectric constant is lessthan or equal to 2.6. In some embodiments, the dielectric constant isless than or equal to 2.5. In some embodiments, the dielectric constantis less than or equal to 2.4. In some embodiments, the dielectricconstant is less than or equal to 2.3. In some embodiments, thedielectric constant is less than or equal to 2.2. In some embodiments,the dielectric constant is less than or equal to 2.1. In someembodiments, the dielectric constant is less than or equal to 2. In someembodiments, the dielectric constant is less than or equal to 1.9. Insome embodiments, the dielectric constant is less than or equal to 1.8.In some embodiments, the dielectric constant is less than or equal to1.7. In some embodiments, the dielectric constant is less than or equalto 1.6. In some embodiments, the dielectric constant is less than orequal to 1.5. In some embodiments, the dielectric constant is less thanor equal to 1.4. In some embodiments, the dielectric constant is lessthan or equal to 1.3. In some embodiments, the dielectric constant isless than or equal to 1.2. In some embodiments, the dielectric constantis less than or equal to 1.1.

In some embodiments, the dielectric constant is from about 1.1 to about2.8. In some embodiments, the dielectric constant is from about 2 toabout 2.8. In some embodiments, the dielectric constant is from about2.1 to about 2.8. In some embodiments, the dielectric constant is fromabout 2.2 to about 2.8. In some embodiments, the dielectric constant isfrom about 2.3 to about 2.8. In some embodiments, the dielectricconstant is from about 2.4 to about 2.8. In some embodiments, thedielectric constant is from about 2.5 to about 2.8. In some embodiments,the dielectric constant is from about 2.6 to about 2.8. In someembodiments, the dielectric constant is from about 2.7 to about 2.8. Insome embodiments, the dielectric constant is from about 2.1 to about2.7. In some embodiments, the dielectric constant is from about 2.1 toabout 2.6.

In some embodiments, the dielectric constant is from about 2 to about2.5. In some embodiments, the dielectric constant is from about 2.1 toabout 2.5. In some embodiments, the dielectric constant is from about2.2 to about 2.5. In some embodiments, the dielectric constant is fromabout 2.3 to about 2.5. In some embodiments, the dielectric constant isfrom about 2.4 to about 2.5. In some embodiments, the dielectricconstant is from about 2 to about 2.4. In some embodiments, thedielectric constant is from about 2.1 to about 2.4. In some embodiments,the dielectric constant is from about 2.2 to about 2.4. In someembodiments, the dielectric constant is from about 2.3 to about 2.4. Insome embodiments, the dielectric constant is from about 2 to about 2.3.In some embodiments, the dielectric constant is from about 2.1 to about2.3. In some embodiments, the dielectric constant is from about 2.2 toabout 2.3. In some embodiments, the dielectric constant is from about 2to about 2.2. In some embodiments, the dielectric constant is from about2.1 to about 2.2.

In some embodiments, the dielectric materials in the present disclosurecan be filled with glass microspheres to further reduce the dielectricconstant to 1.8-2.5.

In some embodiments, the dielectric constant of the dielectric materialis substantially isotropic. In some embodiments, the dielectric constantof the dielectric material is measured at about 1, 5, or 10 GHz. Inpreferred embodiments, the dielectric constant of the dielectricmaterial is measured at about 5 GHz.

Dissipation Factor (or DF) of Films

In some embodiments, the dissipation factor of the dielectric materialis up to about 0.01, 0.009, 0.008, 0.007, 0.006, 0.005, 0.004, 0.005,0.004, 0.003, 0.002, or 0.001. In some embodiments, the dissipationfactor of the dielectric material is less than or equal to 0.005. Insome embodiments, the dissipation factor of the dielectric material isless than or equal to 0.004. In some embodiments, the dissipation factorof the dielectric material is less than or equal to 0.003. In someembodiments, the dissipation factor of the dielectric material is lessthan or equal to 0.002. In some embodiments, the dissipation factor ofthe dielectric material is less than or equal to 0.001. In someembodiments, the dissipation factor of the dielectric material is fromabout 0.001 to about 0.005. In some embodiments, the dissipation factorof the dielectric material is from about 0.0015 to about 0.0025. In someembodiments, the dissipation factor of the dielectric material is fromabout 0.002 to about 0.005. In some embodiments, the dissipation factorof the dielectric material is from about 0.003 to about 0.005. In someembodiments, the dissipation factor of the dielectric material is fromabout 0.004 to about 0.005.

In some embodiments, the dissipation factor of the dielectric materialis substantially isotropic. In some embodiments, the dissipation factorof the dielectric material is measured at about 1, 5, or 10 GHz. Inpreferred embodiments, the dissipation factor of the dielectric materialis measured at about 5 GHz.

Young's Modulus (or Elastic Modulus) of Films

In some embodiments, the Young's modulus (also referred to as tensile orelastic modulus) of the dielectric material and/or the polymercomposition is about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1,1.5, 2, 3, 4, 5, 6 GPa. In some embodiments, the Young's modulus of acured thermoset composition in the presently disclosed embodiments isabout 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, 3, 4, 5, 6GPa. In some embodiments, the Young's modulus is less than or equal toabout 6 GPa. In some embodiments, the Young's modulus is less than orequal to about 5 Gpa. In some embodiments, the Young's modulus is lessthan or equal to about 4 Gpa. In some embodiments, the Young's modulusis less than or equal to about 3 Gpa. In some embodiments, the Young'smodulus is less than or equal to about 2 Gpa. In some embodiments, theYoung's modulus is less than or equal to about 1 Gpa. In someembodiments, the Young's modulus is from about 0.1 GPa to about 6 GPa.In some embodiments, the Young's modulus is from about 0.1 GPa to about5 GPa. In some embodiments, the Young's modulus is from about 0.1 GPa toabout 3 GPa. In some embodiments, the Young's modulus is from about 0.1GPa to about 2 GPa. In some embodiments, the Young's modulus of thedielectric material is substantially isotropic.

In some embodiments, the dielectric material is a dielectric film,wherein the thickness of the dielectric film is from about 0.25thousandth of an inch (Mil) to about 125 Mil. In some embodiments, thethickness is greater than or equal to 1 micrometer (μm). In someembodiments, individual films or sheets the dielectric material and/orthe polymer composition are stacked and pressed to achieve a thicknessof about 10 Mil to about 125 Mil.

In some embodiments, the dielectric material includes a thicknessvariance of up to about 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%. Insome embodiments, the thickness variance is less than or equal to about10%. In some embodiments, the thickness variance is less than or equalto about 9%. In some embodiments, the thickness variance is less than orequal to about 8%. In some embodiments, the thickness variance is lessthan or equal to about 7%. In some embodiments, the thickness varianceis less than or equal to about 6%. In some embodiments, the thicknessvariance is less than or equal to about 5%. In some embodiments, thethickness variance is less than or equal to about 4%. In someembodiments, the thickness variance is less than or equal to about 3%.In some embodiments, the thickness variance is less than or equal toabout 2%. In some embodiments, the thickness variance is less than orequal to about 1%. In some embodiments, the thickness variance is fromabout 1% to about 10%. In some embodiments, the thickness variance isfrom about 2% to about 9%. In some embodiments, the thickness varianceis from about 3% to about 8%. In some embodiments, the thicknessvariance is from about 4% to about 7%.

Fillers

In some embodiments, the at least one dielectric layer further comprisesa filler. In some embodiments, the filler is selected from the groupconsisting of aluminum hydroxide, magnesium hydroxide, kaolin, talcum,hydrotalcite, calcium silicate, beryllium oxide, boron nitride, glasspowder, silica powder, zinc borate, aluminum nitride, silicon nitride,carborundum, magnesium oxide, zirconium oxide zirconium oxide, mullite,titanium oxide, potassium titanate, hollow glass micro-bead, potassiumtitanate fiber, carborundum single crystal filament, silicon nitridefiber, alumina single crystal fiber, staple glass fiber,polytetrafluorethylene powder, polyphenylene sulfide powder, polystyrenepowder, and combinations thereof. In some embodiments, the dielectriclayer further comprises a flame retardant additive. In some embodiments,the flame retardant additive is a non-halogenated flame retardantadditive. In some embodiments, the non-halogenated flame retardant isselected from the group consisting of a phosphorous-based flameretardant additive, an inorganic-based flame-retardant additive, and acombination thereof. In some embodiments, the at least one dielectriclayer further comprises an auxiliary agent selected from the groupconsisting of heat stabilizers, light stabilizers, ultra-violet lightabsorbers, anti-oxidants, radical stabilizer, anti-static agents,preservatives, adhesion promoters, toughening agents, rubber particles,pigments, dyes, lubricants, mold releasers, blowing agents, fungicides,plasticizers, processing aids, acid scavengers, dyes, pigments,stabilizers, blowing agents, nucleating agents, nanotubes, wettingagents, dispersing agents, synergists, mineral fillers, reinforcingagents, whiskers, inorganic fillers, smoke suppressants, andcombinations thereof. In some embodiments, the at least one dielectriclayer further comprises one or more metal-filled microvias thatpenetrate the dielectric layer.

The dielectric films in the present disclosure can be made, in someembodiments, using combinations of materials, such as functionalizedPPE, such as SA9000 available from Sabic corporation, Triallylisocyanurate, available from Evonik, Tri allyl cyanurate available fromEvonik, and other manufacturers, Cyanate Ester and Bismaleimide Resinssuch as BMI 5100 available from Daiwa Kasei corporation, GMI 2300available from Shin-A T&C (Korea), XAD-620 from Shin-A T&C (Korea). Insome embodiments, organic fillers, such as high impact polystyrene, PTFEpowders, or inorganic fillers such as fused silica, titanium dioxide,silicon nitride, aluminum nitride, boron nitride are added to thedielectric films to improve CTE, thermal conductivity, and/or otherproperties. Spherical or no spherical fillers (e.g., spherical silica),including hollow spherical fillers, may also be used. Flame retardantsuch as Exolit® OP935 or Exolit® OP945 Aluminum Poly Phosphinateavailable from Clariant corporation, SPB100 or Phosphazene availablefrom Otsuka chemical corporation can also be used as a flame retardantfor halogen free applications. Other Phosphorated compounds such asAltexia from Albemarle or PQ 60 from Chin Yee chemicals may also beused, alone or in combination with other flame retardants. Halogenatedflame retardants such as Saytex 8010, Ethylene-1,2-bis(pentabromophenyl)or BT 93 from Albemarle corporation can be used. Copolymers of butadieneand styrene such as Ricon 100, Ricon 184, Ricon 257 and Polymer ofbutadienes such as Ricon 300, Ricon, 130, Ricon 131, Ricon 134, Ricon154, Ricon 156, and Ricon 157 available from Total can be used tocrosslink or as a backbone for the dielectric films. In someembodiments, peroxide curing agents can be used in a curing process.

In some embodiments, a filler of the present disclosure may be may bepresent in the dielectric films from: 0 to 0.1% by weight based on theweight of the dielectric film, 0 to 0.5% by weight based on the weightof the dielectric film, 0 to 1% by weight based on the weight of thedielectric film, 0 to 5% by weight based on the weight of the dielectricfilm, 1 to 5% by weight based on the weight of the dielectric film, 1 to6% by weight based on the weight of the dielectric film, 1 to 7% byweight based on the weight of the dielectric film, 1 to 8% by weightbased on the weight of the dielectric film, 1 to 9% by weight based onthe weight of the dielectric film, 1 to 10% by weight based on theweight of the dielectric film, 10 to 20% by weight based on the weightof the dielectric film, 20 to 30% by weight based on the weight of thedielectric film, 30 to 40% by weight based on the weight of thedielectric film, 40 to 50% by weight based on the weight of thedielectric film, 50% to 60% by weight based on the weight of thedielectric film, 60% to 70% by weight based on the weight of thedielectric film, or up to 70% weight based on the weight of thedielectric film. In some embodiments, a filler of the present disclosuremay be may be present in a dielectric film of the present disclosure inan amount of 0, 0.0001, 0.001, 0.01, 0.02, 0.03, 0.04, 0.05, 0.1, 0.2,0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29,30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, or 60 weight percentbased on the weight of the dielectric film.

Film Thickness

In some embodiments, the average thickness of a dielectric polymer filmdescribed herein is about 0.1 Mil to about 6.0 Mil (e.g., about 0.1 Milto about 1.0 Mil, about 0.1 Mil to about 2.0 Mil, about 0.1 Mil to about3.0 Mil, about 0.1 Mil to about 4.0 Mil, or about 0.1 Mil to about 5.0Mil). In some embodiments, the average thickness of a dielectric polymerfilm described herein is about 0.25 Mil to about 2.5 Mil. In someembodiments, the average thickness of a dielectric polymer filmdescribed herein is about 0.5 Mil to about 2.0 Mil. In some embodiments,the average thickness of a dielectric polymer film described herein isabout 3.0 Mil to about 5.0 Mil. In some embodiments, the averagethickness of a dielectric polymer film described herein is about 0.5Mil. In some embodiments, the average thickness of a dielectric polymerfilm described herein is about 1 Mil. In some embodiments, the averagethickness of a dielectric polymer film described herein is about 1.5 MilIn some embodiments, the average thickness of a dielectric polymer filmdescribed herein is about 5 Mil to about 125 Mil. In some embodiments,the average thickness of a dielectric polymer film described herein isabout 0.1 Mil, 0.2 Mil, 0.3 Mil, 0.4 Mil, 0.5 Mil, 0.6 Mil, 0.7 Mil, 0.8Mil, 0.9 Mil, 1.0 Mil, 1.1 Mil, 1.2 Mil, 1.3 Mil, 1.4 Mil, 1.5 Mil, 1.6Mil, 1.7 Mil, 1.8 Mil, 1.9 Mil, 2.0 Mil, 3.0 Mil, 3.3 Mil, 3.5 Mil, 4.0Mil, 5.0 Mil, or 6.0 Mil.

Peel Strength

In some embodiments, the average peel strength of the film onto anadhered surface (e.g., onto a metal laminate) is from about 1-10 lb/in,2-10 lb/in, 3-10, 4-10, 5-10, 6-10, 7-10, 8-10, or 9-10 lb/in. In someembodiments, the average peel strength of the film onto an adheredsurface (e.g., onto a metal laminate) is from about 3-6 lb/in, 4-6lb/in, or 5-6 lb/in.

Method of Manufacturing Dielectric Materials

Provided herein are methods of manufacturing dielectric materials asdescribed above. In some embodiments, provided herein are methods ofmanufacturing a sheet or film of dielectric materials. In someembodiments, methods of making sheets and films described herein includesolvent casting, melt extrusion, lamination, and coating methods.Non-limiting examples of solvent casting, melt extrusion, lamination,and coating methods can be found, for example, in U.S. PatentApplication Publication Nos. US 2009/0050842, US 2009/0054638, and US2009/0096962, the contents of which are incorporated herein byreference. Further examples of solvent casting, melt extrusion,lamination, and coating methods to form films can be found, for example,in U.S. Pat. Nos. 4,592,885 and 7,172,713, and U.S. Patent ApplicationPublication Nos. US 2005/0133953 and US 2010/0055356, the contents ofwhich are incorporated herein by reference.

The continuous solvent cast process is the preferred method forproviding thin films of the dielectric materials described herein. Thesolvent casting process is capable of providing the compositions withextremely high quality and of uniform thickness. A typical solventcasting process involves 1) dissolving and/or dispersing the components(e.g., polymer, crosslinker, filler, flame retardant, etc.) in a solventto create a varnish; 2) coating the varnish on a substrate (e.g., copperfoil) or casting film (e.g., PET); and 3) evaporation/removal of thesolvent via drying (e.g., drying with a drying oven) to yield a film ofthe polymer composition on a substrate or carrier film. The finalthickness of the film can be controlled, for example, by passing thevarnish through a slot die. In order for the casting process to yield ahigh-quality film, it is important that the polymer dissolves in thevarnish solvent. The residence time and temperature profile of thedrying oven will dictate factors such as the amount of residual solventretained in the film and whether the film is a cross-linked polymercomposition or if it remains an admixture (e.g., has thermoplasticqualities). In some embodiments, the polymer composition is athermoplastic polymer (or thermosetting) composition after the filmcasting and drying process. In some embodiments, the polymer compositionis a crosslinked thermoplastic composition after the film casting anddrying process.

In some embodiments, the sheet or film is provided on a carrier, orrelease, film, such as, but not limited to, PET, release treated PET,biaxially oriented polypropylene, and other common carrier or releaseliners. In some embodiments the sheet or film is provided on a copperfoil. In some embodiments, the film of the polymer composition istack-free to the touch. In some embodiments, in some embodiments thepolymer film composition possesses sufficient plasticity such that itcan be peeled off the carrier film and placed on an object. In someembodiments, the composition on a carrier film can be placed on asubstrate, passed through a roll laminator, and then the carrier filmpeeled away leaving the polymer composition on the new substrate. Insome embodiments, the substrate to be laminated is a copper foil orsheet. In some embodiments, the substrate to be laminated is a coperclad (etched, partially etched, or no etch), or copper unclad fiberglasscore. In some embodiments, the sheet or film is metal clad (e.g.,copper) or unclad. In some embodiments, the sheet or film isunreinforced (e.g., not reinforced, not comprising woven or non-wovenglass fabric, organic woven or non-woven).

In some embodiments, the polymer composition is dispersed in a solventand provide as a vanish composition. In some embodiments, the varnishcomposition is stable for days (e.g., before the varnish gels due to thecrosslinking of the polymer and the crosslinking agent). In someembodiments, the varnish composition is stable for weeks before gellingoccurs. In some embodiments, the varnish composition is stable formonths before gelling occurs. In some embodiments the varnishcomposition is casted on to a carrier film. In some embodiments, thecarrier film is polyethylene terephthalate (PET) or PET that has beentreated to further facilitate the release of the polymer composition. Insome embodiments, the varnish composition is casted on to copper foil.

In preferred embodiments, the dielectric films in the present disclosurecan be carried on substrates such as copper foil or PET. Such copperfoil can include a thickness of about 3 to about 35 microns. In someembodiments, the dielectric films can be coated with a 0.5-5.0-micronthick sputtered copper through e.g., a physical vapor depositionprocess. In some embodiments, the present disclosure includes laminatesthat are made by laminating copper foils coated with the dielectricfilms as described herein, followed by pressing them together throughhot roll lamination of pressing using batch processing with a platenpress.

Printed Circuit Boards Comprising Transmission Lines Formed fromDielectric Polymer Film

In an embodiment, provided herein is a printed circuit board comprisingone or more transmission lines formed of a composition as describedherein (e.g., a dielectric polymer film).

The transmission line may be used as any type of conductive line (e.g.,high-speed conductive line). In some examples, at least one of thetransmission lines is formed in or on an outer layer of the PCB (e.g.,as microstrip of microstrip transmission line). In some examples, atleast one of the transmission lines is formed in or on an inner layer ofthe PCB (e.g., as a stripline). The transmission line may besingle-ended or differential.

At a signal frequency (e.g., signal transmission rate) of 10 GHz, thedissipation factor of at least one of the transmission lines may be0.0010, 0.0015, 0.0020, 0.0021, 0.0022, 0.0023, 0.0024, 0.0025, 0.0026,0.0027, 0.0028, 0.0029, 0.0030, 0.0035, or 0.0040.

The width of at least one of the transmission lines may be between 1 and4 Mils, between 4 and 6 Mils (e.g., 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6,4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9 or 6.0Mils), or greater than 6 Mils (e.g., between 6 and 20 Mils). The unit“Mil” or “mil” refers to 1/1000 of an inch.

In some examples, transmission lines (e.g., a first transmission lineand a second transmission line) may be formed in vertically adjacentlayers of the PCB. In such examples, the thickness of a dielectric layerbetween the first transmission line and the second transmission line maybe less than 3 Mils (e.g., between 0.1 Mils and 3 Mils), between 3 Milsand 5 Mils (e.g., 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0,4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5.0 Mils), or greaterthan 5 Mils (e.g., between 5 and 20 Mils).

In some examples, the transmission line is capable of carrying signalsmodulated using any modulation scheme including, without limitation,pulse amplitude modulation (PAM). The number of pulse amplitude levelsused in the pulse amplitude modulation scheme may be 2, 3, 4, 5, 6, 7,8, 9, 10, 11, 12, 13, 14, 15, or 16.

In some examples, the transmission line is capable of carrying data atdata rate between 28 and 224 Gbps (e.g., 28, 56, 112, or 224 Gbps).

In some embodiments, a PCB comprising one or more transmission linesformed of a composition as described herein may be flexible. Theflexible PCB may, in some embodiments, have an elastic modulus between0.01 GPa and 6 GPa (e.g., 1 GPa, 2 GPa, 3 GPa, 4 GPa, or 5 GPa). Theflexible PCB may, in some embodiments, have an elastic modulus of lessthan or equal to 6 GPa (e.g., less than or equal to 1 GPa, less than orequal to 2 GPa, less than or equal to 3 GPa, less than or equal to 4GPa, or less than or equal to 5 GPa). In some examples, the componentsof the flexible PCB may include one or more sensor devices (e.g.,wearable sensors). In some embodiments, a PCB comprising one or moretransmission lines formed of a composition as described herein may beused to create an antenna. For example, at least one dielectric polymerfilm may be used to manufacture a double sided, or multilayer antenna.

In some examples, the PCB is a component of a computational device(e.g., desktop computer, laptop computer, server, tablet, accelerator,supercomputer, mobile phone, etc.) or a networking device (e.g., switch,router, access point, modem, etc.). Such computational or networkingdevices may be configured to use the PCB to communicate with remotedevices using any suitable wireless communication technology or standard(e.g., 4G, 5G, 6G, etc.).

For use in a process of manufacturing a PCB comprising one or moretransmission lines formed of the dielectric polymer film, the film maybe provided in bonding sheet form or in cured form (e.g., in the form ofa c-stage core laminate).

Printed Circuit Boards Comprising Dielectric Materials

In an embodiment, provided herein is a printed circuit board comprisingone or more insulating layers (also referred to herein as a “dielectriclayer,” “dielectric material,” or “dielectric film”), wherein theinsulating layer comprises a composition as described herein.

Advanced PCBs may include components embedded in the substrate (e.g.,capacitors, resistors, or active devices). PCBs can be single sided (onecopper layer), double sided (two copper layers) or multi-layer (e.g.,multiple copper layer separated by dielectric materials) that allow highcomponent density. Multilayer PCBs are complex composite structuresgenerally comprising a series of layers of reinforced resin and copperfoil. Conductors on different layers may be connected with “vias” orplated-through holes. Laminates for PCB applications are manufacturedvia a process known as prepreging.

In some embodiments, the printed circuit board comprises a hybriddesign, wherein the central core is a fiberglass-based dielectric (orlaminate), and at least one, or a plurality, of the outer insulatinglayers comprise a polymer dielectric film. In some embodiments, thehybrid design has more than one fiberglass-based dielectric, and atleast one, or a plurality, of the other insulating layers comprise apolymer dielectric film. In some embodiments, the printed circuit boardis multilayered, double sided or single sided. In some embodiments, thesheet or film is used in a sequential build-up process. In someembodiments, the sheet or film is used in a sequential build-up process,where in the central core is fiberglass laminate.

A printed circuit board (e.g., an HDI-PCB) described herein may compriseone or more dielectric material (e.g., one or more dielectric films) asdescribed herein and one or more copper layers.

In some embodiments, the stress below the T_(g) of at least one of theone or more dielectric film is 15 to 30 MPa, or 15 to 20 MPa.

In some embodiments, the stress above the T_(g) of at least one of theone or more dielectric film is 1 to 3 MPa (e.g., about 1.5 MPa).

The tensile stress imposed on the copper during assembly of a PCB (as inoverstress failure mode) is given as:

$\begin{matrix}{\sigma_{Cu} = {\int_{T_{amb}}^{T_{assem}}{\left( {\alpha_{Eq} - \alpha_{Cu}} \right) \times E_{Cu}{dT}}}} & (1)\end{matrix}$where σ_(Cu) is the tensile stress in copper in the z-direction, α_(Eq)and α_(Cu) are the coefficients of thermal expansion in the z-directionfor the equivalent material (dielectric and copper together) and forpure copper, respectively, T_(assem) and T_(amb) are the assemblytemperature and the ambient temperature, respectively, and E_(Cu) is theYoung's modulus for the copper in the z-direction.

The equivalent coefficient of the dielectric material and copper isgiven by rule of mixtures as:

$\begin{matrix}{\alpha_{Eq} = \frac{\left( {{\alpha_{Di}V_{Di}E_{Di}} + {\alpha_{Cu}V_{Cu}E_{Cu}}} \right)}{E_{Eq}}} & (2)\end{matrix}$E _(Eq) =V _(Di) E _(Di) +V _(Cu) E _(Cu)  (3)

where E_(Di), E_(Cu), and E_(Eq) are the moduli for the dielectric,copper, and the equivalent material in the Z-direction, respectively,α_(Di), α_(ce), and α_(Eq) are the z-direction coefficients of thermalexpansion for the dielectric, copper, and the equivalent material,respectively, and V_(Di) and V_(Cu) are the volume fractions of thedielectric and the copper, respectively, in the area of influence in thecircuit board.

The above equations can also be used for calculation above the glasstransition temperature of the dielectric, T_(g) by substitutingappropriate quantities.

Since the coefficients of thermal expansion below T_(g) and above T_(g)as well as the moduli in the Z-direction can be approximated as constantvalued, equation (1) can be rewritten as:σ_(Cu)=(α_(Eq) _(b) −α_(Cu))(T _(g) −T _(amb))E _(Cu) _(e)+(α_(Eqa)−α_(Cu))(T _(yield) −T _(g))E _(Cue)+(α_(Eqa)−α_(Cu))(T_(assem) −T _(yield))E _(Cu) _(p)   (4)where the subscript b indicates below T_(g), the subscript a indicatesabove T_(g), the subscript e indicates elastic, the subscript pindicates plastic, and T_(yield) is the temperature at which the stressin the copper exceeds the yield stress for copper.Stress/Strain During Thermal Cycling and Operating Conditions

The tensile stress imposed on the copper during operating conditions isgiven as:

$\begin{matrix}{\sigma_{Cu} = {\int_{T_{LB}}^{T_{UB}}{\left( {\alpha_{Eq} - \alpha_{Cu}} \right)E_{Cu}{dT}}}} & (5)\end{matrix}$where T_(LB) and T_(UB) are the lower and upper bound Temperaturesrespectively of the operating range.

Since the coefficients of thermal expansion below T_(g) and above T_(g)as well as the moduli in the Z-direction can be approximated as constantvalued, equation (5) can be rewritten as:

a) If the upper bound is above T_(yield), but below T_(g):σ_(Cu)=(α_(Eq) _(b) −α_(Cu))(T _(yield) −T _(LB))E _(Cu) _(e) +(α_(Eq)_(b) −α_(Cu))(T _(g) −T _(yield))E _(Cu) _(p)   (6)

b) If the upper bound of operating condition is below T_(yield):σ_(Cu)=(α_(Eq) _(b) −α_(Cu))(T _(UB) −T _(LB))E _(Cu) _(e)   (7)The total strain for the copper would be the sum of the elastic andplastic strain.

a) If the strain is plastic

$\begin{matrix}{\varepsilon_{Cu} = {\frac{\sigma_{Y,{Cu}}}{E_{Cu_{e}}} + \frac{\sigma_{Cu} - \sigma_{Y,{Cu}}}{E_{Cu_{p}}}}} & (8)\end{matrix}$where ε_(Cu) is the copper strain and σ_(Y,Cu) is the yield stress forcopper

b) If the strain is elastic:

$\begin{matrix}{\varepsilon_{Cu} = \frac{\sigma_{Cu}}{E_{Cu_{e}}}} & (9)\end{matrix}$

If equation (9) is applicable, implying that the copper strain is belowyield, the failure mode changes to high cycle fatigue which is akin toalmost infinite life in the context of the use of the device.

The dielectric materials as described herein can be used, for example inthe printed circuit board industry. For example, dielectric films (notreinforced with glass fabric) with low T_(g) low modulus, and/or low CTEin buildup layers can be used in, for example, high-density interconnect(HDI) printed circuit boards to enable higher reliability and increasedinterconnect density. In other embodiments, dielectric films enable theuse of stacked vias which would survive assembly and have a high fatiguelife under the desired operating conditions.

The benefits include more isotropic properties, homogeneity, and abilityto reach dielectric thicknesses below 25 micrometers, improveddielectric spacing, enhancing adhesion to materials including metalssuch as copper, increased microvia reliability, toughening of the matrixand removal of the weave effect which plagues the woven fabricreinforced composites and causes skew or timing issues in high-speeddigital transmission over printed circuit boards. High-densityinterconnect boards that are used for IOT devises, camera modules,infotainment systems, mobile phones, tablets and other consumer devicesin addition to chip packaging, standard double and single sided boards,motherboards, sequential lamination boards, high and standard layercount boards, flexible boards would greatly benefit from the use of thisnew technology. Further, Potential improvement in lasability andincreased throughput due to absence of glass, ability to breaking thedielectric thickness barrier, a potential 20-30% thickness reduction inboards, weight reduction for printed circuit boards, capability todecrease stresses on copper plated vias, reduced Z expansion increasingmicrovia reliability, thickness control an improved crack resistance aresome of the benefits expected from the technology. These metal clad orunclad films or sheets also help solve the differential skew problemsdue to their homogenous, isotropic properties in the film ornon-reinforced form (no woven reinforcements).

In some embodiments, a sheet or film of dielectric materials is providedon a carrier, or release, film, such as, but not limited to, PET,treated or surface modified PET, biaxially oriented polypropylene, andother common carrier or release liners. In some embodiments, the polymercompositions possess sufficient plasticity such that as films, they canbe peeled off the carrier and placed on an object. In some embodiments,the composition on a carrier film can be placed on a substrate, passedthrough a laminator, and then the carrier film peeled away, leaving thepolymer compositions on the new substrate. In some embodiments, thesubstrate to be laminated is a copper foil or sheet. In someembodiments, the substrate to be laminated is a coper clad (etched,partially etched, or no etch), or copper unclad fiberglass core. In someembodiments, the sheet or film is metal clad (e.g., copper) or unclad.In some embodiments, the sheet or film is unreinforced (e.g., notreinforced, not comprising woven or non-woven glass fabric, organicwoven or non-woven fibers (e.g., micro or nano-sized inorganic ororganic fillers)).

Methods of Manufacturing a PCB Comprising Dielectric Materials

In an embodiment, a procedure for forming laminates for printed circuitboards involves such operations as:

-   -   A. One or more sheets of prepreg are stacked or laid-up in        alternating layers with one or more sheets of a conductive        material, such as copper foil, if an electrical laminate is        desired.    -   B. The laid-up sheets are pressed at elevated temperature and        pressure for a time sufficient to fully bond the prepreg        composition and form a laminate. The temperature of this        lamination step is usually between 100° C. and 230° C. The        lamination step is usually carried out for a time of from 1        minutes to 200 minutes, and most often between 10 minutes to 90        minutes. The lamination step may optionally be carried out at        higher temperatures for shorter times (such as in continuous        lamination processes) or for longer times at lower temperatures        (such as in low energy press processes).    -   C. Optionally, the resulting laminate, for example, a        copper-clad laminate, may be post-treated for a time at high        temperature and ambient pressure. The temperature of        post-treatment is usually between 120° C. and 250° C. The        post-treatment usually is between 30 minutes and 12 hours.

In an embodiment, provided herein is a method of making or assembling aprinted circuit board, comprising incorporation of a sheet or film asdescribed herein. In some embodiments, said board is a high-densityinterconnect board (HDI board). In some embodiments, said board is usedfor semiconductor chip packaging applications. In some embodiments, thesheet or film serves the purpose of eliminating skew betweendifferential lines. In some embodiments, the sheet or film is placedbelow the top copper sheet to eliminate pad cratering during lead freeassembly. In some embodiments, the sheet or film is used for fillingheavy copper (>3 Ounce/Sft) layers. In some embodiments the film is usedto enhance the thermal conductivity for applications in packaging LEDsor for other high-power devices and in general for improving thermalconductivity in printed circuit boards. In some embodiments, the sheetor film clad on both sides is used for embedded capacitance layers. Insome embodiments, the sheet or film is used for embedding silicon orother interposer materials used in 2.5 D chip packaging applications orother embedded component packaging.

In some embodiments, a printed circuit board is a high-densityinterconnect (HDI) printed circuit board. HDI printed circuit boardsdiffer from other PCBs in the sense that HDI-PCBs use build-uptechnology in which a board is sequentially built-up layer-by-layer asopposed to conventional multilayer processes which use significantlyfewer process steps. HDI is widely used for applications in whichsmaller sized circuit boards are preferred. For many systems in whichHDI-PCBs are used, it is desirable to reduce the area of the PCB whileincreasing its functionality. Such advancements are generally driven byminiaturization of components, driven by mobile computing, 4 G and 5Gapplications, avionics, and military applications. To achieve thesegoals, successive generations of HDI-PCBs have generally used thinnerand thinner dielectric materials, and laser drilled microvias.

In some embodiments, the printed circuit board is of the type 1+n+1,wherein the n layers can be a subassembly of multiple layers, in mostcases the minimum value of n is 2 which means a double-sided corelaminate. The 1 buildup layer on either side with these embodiments ismade with the film comprising polymer. In some embodiments, the printedcircuit board is multilayered, double sided or single sided. In someembodiments, the sheet or film is used in a sequential build-up process.In some embodiments the printed circuit board is a high-densityinterconnect (HDI) printed circuit board. In some embodiments, thehigh-density interconnect printed circuit board using buildup layerscomprising polymer dielectric films is an i+n+i construction where i isgreater than or equal to 2. In some embodiments, the buildup layers ofthe HDI 1+n+1 construction or i+n+i construction where i is greater thanor equal to 2 use a polymer dielectric film with a thickness of between0.25 Mil and 4 mil. In some embodiments the buildup layers comprisingpolymer are used for any-layer HDI boards and have a thickness between0.25-4 Mils. In some embodiments, the buildup layers of the HDI 1+n+1construction or i+n+i construction where i is greater than or equal to 2or any-layer HDI are fabricated with subtractive etching techniques. Insome embodiments, the buildup layers of the HDI 1+n+1 construction ori+n+i construction where i is greater than or equal to 2 or any-layerHDI are fabricated with modified semi additive (mSAP) or fully additivetechniques. In some embodiments, the build-up layers comprising polymerdielectric films are sputtered with a thin layer of copper. In someembodiments the build-up layers have a nano layer of copper on one sideof their surface.

There are also other methods that are used to make prepregs andlaminates for PCB applications, such as hot melt method where a B-stagedepoxy is melted and pressed on to the reinforcement substrate.

Dielectric layers of PCBs may contain via holes. In some embodiments,the via holes may be filled with sheet or film by placing them directlyover the area that requires the fill, including holes, gap betweentraces or to encapsulate the traces. This would include use inconjunction with copper (e.g., heavy copper), where resin filling byother means is difficult. The resin filling can be carried out acrossthe entirety of the board or focused on only small areas.

In some embodiments, a thin layer (e.g., a very thin layer) of thepolymer composition is used between the metal (e.g., copper) and thethermoset or thermoplastic material to which the metal is to be bonded.In some embodiments, a thin layer (e.g., a very thin layer) of thepolymer composition between the top metal layer of a printed circuitboard and the thermoset or thermoplastic material to which the metal isto be bonded.

Definitions

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as is commonly understood by one of ordinary skillin the art to which this disclosure pertains.

The articles “a” and “an” may be used herein to refer to one or to morethan one (i.e. at least one) of the grammatical objects of the article.By way of example “an analogue” means one analogue or more than oneanalogue.

All ranges recited herein include the endpoints, including those thatrecite a range “between” two values.

As used herein, “about” will be understood by persons of ordinary skillin the art and will vary to some extent on the context in which it isused. If there are uses of the term which are not clear to persons ofordinary skill in the art given the context in which it is used, “about”will mean up to plus or minus 10% of the particular term.

As used herein, “thermoplastic” or “thermoplastic polymer composition”is understood to mean a plastic material or polymer that becomes pliableor moldable above a specific temperature and solidifies upon cooling.

As used herein, “thermoset,” “thermosetting,” “thermosetting material,”or “thermosetting polymer composition” is understood to mean a polymeror resin in a soft solid or viscous state that changes irreversibly intoan insoluble polymer network by curing and which, once hardened, cannotbe reheated and melted back to a liquid form.

As used herein, “printed circuit board” refers to a mechanical supportand electrically connected system of electronic, optical and/oropto-electronic components. For example, a printed circuit can be aprimary insulating substrate (e.g., FR-4 glass epoxy) with a thin layerof copper foil lamination on one or both sides of the substrate. As usedherein “printed circuit board component or part” refers to electronic,optical and/or opto-electronic components of the PCB, (e.g., electronic,optical, and/or opto-electronic components connected through conductivetracks, pads, or other features that may be etched from copper sheetslaminated onto a non-conductive substrate).

As used herein, the term “microvia” may refer to a via through a singlelayer of a PCB.

As used herein, “laminate” refers to a composite comprising one or moreplies of pre-preg, which may be optionally clad with metal (e.g.,copper) foil on one or more sides, that is formed into a final productby the application of heat and pressure. A laminate as described hereinmay be cured or uncured.

As used herein, “pre-preg” refers to a bonding layer of dielectricmaterial which may or may not be reinforced. A polymer composition asdescribed herein, may be used as prepreg for manufacturing the laminate.The thermoplastic polymer is used without any fibrous reinforcement. Apre-preg is also commonly called a bonding sheet.

As used herein, the term “substantially” means to a high degree ofapproximation (e.g., within +/−10% for quantifiable properties) butwithout requiring absolute precision or a perfect match.

As used herein, the terms “T_(g)” and “glass transition temperature” areused interchangeably herein.

EXAMPLES

The below Examples are offered to illustrate the embodiments describedherein and are not to be construed in any way as limiting the scope ofthe embodiments.

Abbreviations: DK: dielectric constant; DF: dissipation factor; CTE:coefficient of thermal expansion.

Example 1—Fabrication and Properties of Dielectric Films

Specific examples of dielectric films with the combination of low T_(g),low modulus, low dielectric constant, and low dissipation factor andsome of their properties are given in Table 1. The compositions wereobtained by either 1) compounding the components in a melt mixerapparatus (i.e., a solvent-free method); or 2) compounding in a solventand uniformly dispersing in a high-speed rotary mixer to give a varnish;subsequently drawling down the varnish with a bar on top of a 2 mil PETfilm, and drying in the oven to a level of <1% retained solvent, toyield the composition as a film of about 1-3 mil thickness. The physicaland electrical data were obtained by stacking piles of dielectric filmand consolidated using a 6×6-inch hydraulic press at a pressure of 250Psi, followed by being cured at 330° F. for 30 minutes to form a filmincluding 0.6 mm in thickness. Ricon 257 is a low molecular weight, highvinyl butadiene-styrene copolymer manufactured by Total (USA). Ricon 154is a low molecular weight, high vinyl polybutadiene resin manufacturedby Total (USA). KR05 is high molecular weight, predominately1,4-addition styrene butadiene copolymer manufactured by Ineos(Germany). SR8983 is high molecular weight, predominately 1,4-additionstyrene butadiene copolymer manufactured by Lion Elastomers (USA).SA9000 is methacrylate terminated polyphenylene ether manufactured bySABIC (USA). GMI 5100 is a bis maleimide manufactured by SHIN-A T&C(Korea). The filler and phosphorous-based flame retardant OP935 isExolit® OP935 manufactured by Clariant (Europe). GB are glassmicrospheres manufactured by 3M (USA). Fused silica isteco-sil-10manufacture by Imerys Refractory Minerals (USA). PTFE powderis SST-4 mg manufactured by Shamrock Technologies (USA). AGE is allylglycidyl ether from Sigma Aldrich (USA). Dicup-R® is a peroxide catalystmanufactured by Arkema (USA). The reported Dk (dielectric constant) andDf (dissipation factor) values are at 5 GHz obtained with a split postdielectric resonator. The reported CTE values were obtained using athermomechanical analyzer (TMA). The reported Young's Modulus and Tgvalues were obtained using a dynamic mechanical analyzer instrument(DMA). The peel strength measurements correspond to one ounce copperweight values.

TABLE 1 Compound Amount (parts) Components Ex1 Ex2 Ex4 Ex5 Ex6 Ex7 Ex8Ricon 257 30 30 150 200 150 200 300 Ricon 154 KR05 SR8983 100 100 100100 100 100 100 GMI 5100 4 4 5 5 4 5 7 SA9000 10 20 18 22 18 18 29 OP93530 30 55 66 88 Fused Silica PTFE powder GB 45 50 Dicup-R 2 2 3 4 3 4 5AGE DK 2.51 2.51 2.48 2.49 2.14 2.18 2.48 DF .0022 .0022 .0025 .0023.0025 .0025 .0023 tensile .76 .73 1.09 .58 0.72 .41 .48 modulus (Gpa)tensile .058 .024 .056 .032 .044 .030 .019 modulus @ T_(g) (GPa) CTE(ppm/° C. 200 222 120 238 115 148 213 from 50- 260° C.) DMA T_(g) 112104 111 109 109 107 103 (° C.) Peel Strength 2.9 4.1 3.5 4.3 2.9 3.2 3.9(lb/in) Compound Amount (parts) Components Ex9 Ex10 Ex11 Ex12 Ex13 Ex14Ricon 257 300 30 30 30 100 Ricon 154 30 KR05 30 SR8983 100 100 100 100100 GMI 5100 7 10 10 2.5 10 SA9000 28 5 10 OP935 30 30 29 Fused Silica60 90 PTFE powder 40 GB 67 Dicup-R 5 2 2 2 2 AGE 3 3 DK 2.16 2.71 2.712.39 2.49 2.53 DF .0025 .0026 .0026 .0018 .0028 .0022 tensile .91 .60.97 1.73* modulus (Gpa) tensile 0.037 .030 .078 modulus @ T_(g) (GPa)CTE (ppm/° C. 117 224 183 233 239 from 50- 260° C.) DMA T_(g) 85 94 100(° C.) Peel Strength 4.1 4.3 3.1 4.9 1.9 4.2 (lb/in) *Flexural modulusmeasured

Example 2—Properties in Dielectric Films of the Present Disclosure

Table 2 shows improved properties in dielectric films in the presentlydisclosed embodiments in comparison with known films in the art,resulting in improved PCB performance. The improved properties includedreduced insertion loss (“Loss at 16 GHz dB/inch” in Table 2) anddielectric constants (“DK” in Table 2), as described below in furtherdetail. The improved properties also included reduced stress (“PlasticStrain” in table 2) on vias and therefore increased PCB reliability.

Calculations Based on Dielectric Constant, Dissipation Factor, and Skew

The speed data in Table 2 was generated (e.g., by calculation) usingcommercial electronic design automation software, such as Gauss 2D andGauss Stack, from Avishtech.

The insertion loss ac was calculated by the following equation:

$\alpha_{c} = {\frac{R_{m}\sqrt{\varepsilon}}{2Z_{0}}\frac{dZ_{0}}{dl}}$

where

${R_{m} = \sqrt{\frac{\omega\mu}{2\sigma}}},$ω is the angular frequency, μ is the magnetic permeability (e.g., equalto 4 π X 10⁻⁷ H/m for copper), u is the electrical conductivity (whichis equal to 5.88×10⁷ S/m for copper), w is the width, Z₀ is thecharacteristic impedance, and E is the permittivity of the material.

The current state of the art for comparison included 3.5 mil thickdielectrics and 0.5 ounce copper. The dielectric constants for thedielectric materials used in the state of the art may be at least 3.2(e.g., 3.2, or 3.4), as shown in Table 2. The insertion loss for thedielectric materials used in the state of the art may be at least 1.24,as shown in Table 2. The transmission lines were run as differentialpairs with an impedance of around 85-100 ohms. The state of the art mayuse woven glass fabric with low-dielectric constant (“DK” in Table 2)glass reinforcement, where the “DK” is a value of at least 3.2 and a Tgof at least 170° C. in Table 2. Since the dielectric constants of glassand resin are quite dissimilar, this may lead to skew problems which canbe mitigated to some extent by rotation or hardware such as re-timers.

In comparison, as also shown in Table 2, the dielectric films in thepresently disclosed embodiments (e.g., Ex1, Ex2, and Ex4-Ex11) includednon-fiber weave reinforced film with a dielectric constant equal to orless than 2.8 (e.g., 2.8, 2.6, 2.4, or 2.1), enabling a wider linewithout skew and reduced insertion loss, and enabling communications atfaster rates for longer lengths.

Calculations Based on Tg/Modulus

Assumptions of copper properties and dimensions for an HDI-printedcircuit board with copper filled vias are provided in Table 3.

TABLE 3 Value Units Copper Properties Modulus Elastic 117 GPa ModulusPlastic 1.15 GPa Poisson ratio 0.35 CTE of Copper- 10−6 m/m 17.6 YieldStrength 65 MPa Yield Strain 0.056 Percent Ambient 25.000 ° C. Microviadimensions Outside diameter of the microvia 0.1 mm Inner diameter of themicro via filled Dielectric diameter of influence 0.4 mm 0.5 mm pitchDielectric Volume Fraction 0.938 Copper Volume Fraction 0.063

Sample calculations based on the parameters provided in Table 3 and theempirically derived physical properties of the dielectrics in Table 1were performed. Table 4 illustrates a comparison of a PCB fabricatedusing a typical existing material with a 170° C. T_(g) prepreg versusone made with a low Dk, DF, Modulus, and T_(g) dielectric of Ex9 fromTable 1.

TABLE 4 State of Dielectric material the Art Ex10 Tg of dielectric layer170 90.0 ° C. Ambient 25.000 25.000 ° C. CTE of dielectric below Tg per° C. 60.00 117.00 10−6 m/m CTE of prepreg dielectric 264.00 117.00 10−6m/m above TG per ° C. Modulus of Resin below Tg 6.00 0.47 GPa Modulus ofthe dielectric in Z 6.00 0.47 GPa direction Modulus of the resin aboveTg 0.20 0.04 GPa CTE - Alpha l below Tg equivalent 35.52 22.74 10−6 m/mper ° C. below Copper yield CTE - Alpha 2 below copper elastic 23.7618.07 10−6 m/m limit and above Tg equivalent per ° C. CTE - Alpha 2above copper elastic 59.47 103.15 10−6 m/m limit and below Tg equivalentper ° C. CTE - Alpha 3 above Tg and copper 195.72 49.82 10−6 m/m elasticlimit equivalent per ° C. Stress below Copper Yield 65.00 39.07 MPaStress above copper yield and MPa below Tg Stress above Tg to 250 86.8838.90 MPa Total stress 86.88 38.90 MPa Plastic Strain for reflow 1.9020.00% Percent

The use of a substantially isotropic, low T_(g) and low Modulus, low Dkand Low Df films of the disclosure demonstrate data that show that thecopper stresses stay below the yield strength, whereas with the existinghigher T_(g) materials in the Art, the stresses exceed the yieldstrength and lead to permanent deformation leading to early failure—insome cases, during assembly, itself. Since, for example, the stresscalculated using the direction film Ex9 is lower than the yield stressof the copper, the copper behaves in an elastic manner and is notsubject to low cycle fatigue, indicating very high reliability. Incontrast, a typical existing material as in use currently in the Art (inthis case a 170° C. T_(g) material prepreg) results in much higherstresses. These results show the possibility of failure due tooverstress and fatigue due to plastic strain, when the current set ofmaterials is used.

TABLE 2 Computed stress DMA Line up to Tensile Tg Deg width reflowInsertion Tensile Modulus CTE C max 100 250° C. loss Skew Dk @ Df @ 5Modulus Gpa @ PPM/° C. Tan Ohms in Plastic dB/inch pS/ 5 GHz GHz Gpa Tg50-260 Delta differential copper strain 16 GHz inch State of the art3.2000 0.0025 6.00 0.1200 148.0 170.0 2.85 86.9 1.90% 1.240 3.2 High TgEx1 2.5059 0.0022 0.76 0.0584 200.0 112.0 3.55 77.5 1.09% 0.990 0.0 Ex22.5120 0.0022 0.73 0.0246 222.0 104.0 3.44 73.4 0.73% 0.990 0.0 Ex32.4847 0.0025 1.09 0.0560 120.0 111.0 3.48 65.1 0.01% 1.000 0.0 Ex42.4928 0.0023 0.58 0.0319 238.0 109.0 3.47 75.5 0.91% 0.990 0.0 Ex52.1366 0.0025 0.72 0.0436 115.0 109.0 4.04 39.5 0.00% 0.880 0.0 Ex62.1801 0.0025 0.41 0.0304 148.0 107.0 3.97 29.4 0.00% 0.900 0.0 Ex72.4794 0.0023 0.44 0.0194 213.0 103.0 3.49 45.9 0.00% 0.980 0.0 Ex82.1556 0.0025 0.91 0.0368 117.0 90.0 4.01 38.9 0.00% 0.890 0.0 Ex92.7100 0.0026 0.60 0.0295 224.0 94.0 3.18 65.1 0.01% 1.080 0.0 Ex102.7100 0.0027 0.97 0.0782 183.0 100.1 3.18 79.4 1.25% 1.080 0.0 EX 5, 6,7, 8 show no plastic strain which means very high reliability, otherfilms show much lower plastic strain compared to the state of art whichmeans chances of failure are greatly reduced. The Insertion losscalculation are run for a 3.5 mil Dielectric at 16 GHz. All films showinsertion loss below 1.1 dB/inch and most be low 1.0 db/inch

The stresses were calculated for other dielectrics films described inTable 1. As shown in Table 2, these substantially isotropic, low T_(g),low modulus, low Dk and low Df materials possess either zero plasticstrain, or substantially less plastic strain, when compared to state ofthe art, high T_(g) materials. Additionally, as show in Table 2, thisdisclosure bestows lower insertion loss. Thus, demonstrating that bothhigher reliability and higher-speed PCB can be fabricated using thisdisclosure.

EQUIVALENTS

Those skilled in the art will recognize, or be able to ascertain, usingno more than routine experimentation, numerous equivalents to thespecific embodiments described specifically herein. Such equivalents areintended to be encompassed in the scope of the following claims.

What is claimed is:
 1. A dielectric thermosetting polymer compositionconfigured as a base layer in a printed circuit board, wherein thedielectric thermosetting polymer composition has: (i) a glass transitiontemperature less than 135° C.; (i) a dielectric constant less than 2.8;and (iii) tensile modulus less than or equal to 3 GPa when the averagetemperature of the dielectric thermosetting polymer composition is belowthe glass transition temperature (T_(g)) of the dielectric thermosettingpolymer composition; wherein the tensile modulus is substantiallyisotropic.
 2. The dielectric thermosetting polymer composition of claim1, wherein the polymer composition has a dissipation factor of less thanabout 0.01.
 3. The dielectric thermosetting polymer composition of claim1, wherein the polymer composition has a dissipation factor of less thanabout 0.006.
 4. The dielectric thermosetting polymer composition ofclaim 1, wherein the glass transition temperature of the polymercomposition is less than about 130° C.
 5. The dielectric thermosettingpolymer composition of claim 1, wherein the tensile modulus is less than2 GPa when the average temperature of the polymer composition is belowthe glass transition temperature (TO of said polymer composition.
 6. Thedielectric thermosetting polymer composition of claim comprising analkene-containing polymer.
 7. A printed circuit board comprising thedielectric thermosetting polymer composition of claim
 1. 8. A printedcircuit board, comprising: (i) a core layer; (ii) the dielectricthermosetting polymer composition of claim 1 disposed on a first side ofthe core layer; and (iii) one or more vias penetrating through thedielectric thermosetting polymer composition.
 9. The printed circuitboard of claim 8, wherein the core layer is a fiberglass-based corelayer.